Aerogel vs Fiberglass vs Mineral Wool vs Spray Foam: Which Insulation Wins, and When
There is no best insulation. There is the best insulation for your constraint, and the constraint is usually depth or budget. Aerogel, fiberglass, mineral wool, and spray foam each win a different corner of that trade.
Aerogel blankets in the directory publish thermal conductivity 13 to 21 mW/m·K, the lowest of the four (Ningbo Surnano lists the low end at 13), which is exactly why they cost the most. Here is the honest matchup.
The two numbers that sort them
| Material | R-value per inch (approx) | Relative cost | Wins when |
|---|---|---|---|
| Aerogel | R-8 to R-10 | Highest | Space or weight is the constraint |
| Spray foam (closed cell) | R-6 to R-7 | Middle | You need an air seal plus moderate R |
| Mineral wool | R-3 to R-4 | Low to middle | You need fire or temperature, cheaply |
| Fiberglass | R-3 to R-4 | Lowest | You have the cavity depth and a budget |
Aerogel packs the most R into the least thickness. It reaches a target R in roughly two-thirds the thickness of closed-cell spray foam and about a third of fiberglass. If thickness is the thing you are short of, that ratio is the whole reason aerogel exists.
Aerogel also costs the most, by a wide margin. Fiberglass is the cheapest per area, mineral wool and foam sit in the middle, and aerogel runs several times the cost of fiberglass for the same coverage. The premium buys thinness. If you are not short on space, you are paying for a property you do not need.
What each one wins
Fiberglass takes the open cavity on budget: attics, new stud walls, anywhere with depth to spare and a low cost target. It is the default for good reason.
Mineral wool covers the jobs that need fire resistance or higher temperature at a still-low price: party walls, industrial lines, any surface where a code or the heat rules fiberglass out.
Spray foam earns its place where you need air-sealing and moderate R in one step, and cavities too irregular to fit a batt. It insulates and seals at once.
Aerogel takes the jobs where space or weight is the binding constraint: retrofits, thin walls, pipe and equipment, vehicles, offshore. It is the only one of the four that reaches high R in a thin, light profile.
The honest line
Do not buy aerogel to upgrade a wall that has room for cheap thickness. The premium pays off only when you are out of depth or weight. A new stud bay with a deep cavity wants a thicker layer of something cheaper, not a thin layer of the priciest material on the list.
And do not compare any of these on thermal conductivity alone. Compare on R-per-inch and installed cost for the space you have. A material that is cheaper per square foot but needs three times the thickness stops being cheaper the moment that thickness will not fit.
Where this leaves you
AerogelHub catalogs aerogel suppliers, not fiberglass or foam, so read this as a neutral call rather than a sales pitch. If your constraint is budget and you have the depth, one of the other three is your answer and this is the wrong directory. If your constraint is space or weight, aerogel is worth pricing.
If aerogel fits your job, filter the directory by form and temperature, then compare your finalists side by side in the table.